Lateral Resistance of Ring-shank Nail Connections in Southern Pine Lumber

Ring-shank nails are used in engineered structures with lateral connection design values based on theoretically derived equations which were validated only for common nails. The goal of this study was to quantify the input parameters and lateral connection strength of several types of ring-shank nails in Southern Pine lumber and critically evaluate the applicability of the theoretical equations for ring-shank nails. Two sizes of galvanized and ungalvanized, hardened steel ring-shank nails from two manufacturers were studied. The hardened, ring-shank nails carried significantly higher loads than the common wire nails studied. Because the current method of determining yield load does not give adequate credit to hardened, ring-shank nails, an alternate method is proposed

Withdrawal Strength of Ring-shank Nails Embedded in Southern Pine Lumber

Ring-shank nails are used extensively in post-frame construction due to their superior performance, yet surprisingly little testing has been done on nail sizes above 12d. Experience in the post-frame industry suggests that published allowable design values for ring-shank nails may be overly conservative and need revision. The goal of the research reported herein was to characterize the withdrawal strength of ring-shank nails embedded in Southern Pine lumber. Three sizes ofgalvanized and ungalvanized (bright) ring-shank nails from two manufacturers were studied. Ring-shank nails had approximately twice the withdrawal resistance of smooth-shank nails of the same diameter. Galvanizing slightly reduced withdrawal strength (approximately 8%) due to partial filling of the threads. Nail head pull-through was studied as a possible failure mode. Even allowing for galvanizing and head pull-through, strong evidence is presentedfor increasing withdrawal design valuesfor ring-shank nails

Threaded-nail Fasteners - Research and Standardization Needs

Threaded nail fasteners are commonly used in agricultural and commercial post-frame structures, yet there has been insufficient research to fully understand the effect of threads on withdrawal and lateral load resistance. The objective of this article is to review technical information on threaded nail fasteners and to identify problems facing manufacturers, designers, and users of threaded nail fasteners for engineering applications. Recommendations are given concerning research and standardization needs

Neutron density distributions for atomic parity nonconservation experiments

The neutron distributions of Cs, Ba, Yb and Pb isotopes are described in the framework of relativistic mean-field theory. The self-consistent ground state proton and neutron density distributions are calculated with the relativistic Hartree-Bogoliubov model. The binding energies, the proton and neutron radii, and the quadrupole deformations are compared with available experimental data, as well as with recent theoretical studies of the nuclear structure corrections to the weak charge in atomic parity nonconservation experiments.Comment: 16 pages, RevTex, 11 eps figs, submitted to Phys. Rev.

ICP polishing of silicon for high quality optical resonators on a chip

Miniature concave hollows, made by wet etching silicon through a circular mask, can be used as mirror substrates for building optical micro-cavities on a chip. In this paper we investigate how ICP polishing improves both shape and roughness of the mirror substrates. We characterise the evolution of the surfaces during the ICP polishing using white-light optical profilometry and atomic force microscopy. A surface roughness of 1 nm is reached, which reduces to 0.5 nm after coating with a high reflectivity dielectric. With such smooth mirrors, the optical cavity finesse is now limited by the shape of the underlying mirror

Solutions to the Wheeler-Dewitt Equation Inspired by the String Effective Action

The Wheeler-DeWitt equation is derived from the bosonic sector of the heterotic string effective action assuming a toroidal compactification. The spatially closed, higher dimensional Friedmann-Robertson-Walker (FRW) cosmology is investigated and a suitable change of variables rewrites the equation in a canonical form. Real- and imaginary-phase exact solutions are found and a method of successive approximations is employed to find more general power series solutions. The quantum cosmology of the Bianchi IX universe is also investigated and a class of exact solutions is found.Comment: 21 pages of plain LaTeX, Fermilab-Pub-93/100-

Static Response Function for Longitudinal and Transverse Excitations in Superfluid Helium

The sum rule formalism is used to evaluate rigorous bounds for the density and current static response functions in superfluid helium at zero temperature. Both lower and upper bounds are considered. The bounds are expressed in terms of ground state properties (density and current correlation funtions) and of the interatomic potential. The results for the density static response significantly improve the Feynman approximation and turn out to be close to the experimental (neutron scattering) data. A quantitative prediction for the transverse current response is given. The role of one-phonon and multi-particle excitations in the longitudinal and transverse channels is discussed. (Phys.Rev.B, in press)Comment: 19 pages (plain TeX) and 3 Figures (postscript), UTF-26

Cosmological entropy and generalized second law of thermodynamics in F(R,G)F(R,G) theory of gravity

We consider a spatially flat Friedmann-Lemaitre-Robertson-Walker space time and investigate the second law and the generalized second law of thermodynamics for apparent horizon in generalized modified Gauss Bonnet theory of gravity (whose action contains a general function of Gauss Bonnet invariant and the Ricci scalar: $F(R,G)$). By assuming that the apparent horizon is in thermal equilibrium with the matter inside it, conditions which must be satisfied by $F(R,G)$ are derived and elucidated through two examples: a quasi-de Sitter space-time and a universe with power law expansion.Comment: 10 pages, minor changes, typos corrected, accepted for publication in Europhysics Letter

Sequential motif profile of natural visibility graphs

6 figures captioned6 figures captione

Higher-Derivative Quantum Cosmology

The quantum cosmology of a higher-derivative derivative gravity theory arising from the heterotic string effective action is reviewed. A new type of Wheeler-DeWitt equation is obtained when the dilaton is coupled to the quadratic curvature terms. Techniques for solving the Wheeler-DeWitt equation with appropriate boundary conditions shall be described, and implications for semiclassical theories of inflationary cosmology will be outlined.Comment: 11 pages TeX. A term has been removed from equation (13